1. Technical Field
The present disclosure relates to a switching power supply device that controls switching operation of a switching element with respect to an input voltage to control an output voltage.
2. Description of the Related Art
In recent years, energy problems have been noticed, and there is a strong demand on reduction in standby power of a power supply apparatus such as a switching power supply device. For example, a following system is proposed. The system is for lowering an output voltage to reduce power consumption, in a case where power supply from a switching power supply device is unnecessary, such as in a state where a load device is not connected in an AC adapter or in a state where operation of the load device is stopped.
In Unexamined Japanese Patent Publication No. 2012-178934, when a switching circuit causes a main switch to perform switching operation, a level of a ripple voltage superimposed on an output voltage of an AC adapter by energy supplied to a secondary side circuit through a transformer (main transformer) connected to a main switch is detected. Then, whether or not the AC adapter is in a connection state or a non-connection state with a portable computer is determined, and the output voltage is lowered, or a switching cycle is lengthened, so that power consumption is reduced